(1) Field of the Invention
The invention generally relates to means and methods within the construction industry for installing lath and applying plaster material, also known as stucco. More specifically, disclosed embodiments disclose means and methods of applying stucco systems to eliminate or reduce subsequent cracks that often originate at doors and windows.
(2) Description of the Related Art
Lath and stucco material combine to form an integral unit. First, the walls of the structure are waterproofed during the lathing process with two layers of grade D paper or equivalent. Next, a metal lath is installed and secured with 1¼ staples with the intended purpose of providing an ideal surface to support the plaster material. Stucco usually consists of a three coat system with a thickness of ⅞″ and is applied in the following sequence: scratch coat, brown coat and finish coat. This wet cementitious material may crack during the drying process, or more often may crack as a result of building settlement or movement. Cracks most often develop at or near window and door corners where building movements become unevenly dispersed.
The prior art of installation of control joints on exterior stucco walls is often used in an effort to minimize cracks in large or long stucco panels. Although not intentionally created for this purpose, they can also be used at doors and windows. However, control joints add time and expense during the lathing process because several hours of labor are necessary to ensure that it is properly installed. Also, the fact that the product is visible upon finalizing the stucco system may reduce the design appeal of the end product, thereby deterring some builders or architects from using it.
The prior art often resorts to a synthetic material used in acrylic finish coats which may stretch to some extent with building movement and reduce the likelihood of hairline cracks. Unfortunately, exterior acrylic finish coats often fail to exhibit the necessary flexibility to remain intact since most structural cracks develop in the scratch coat and move outward toward the finished surface. Therefore, the superficial nature of acrylic finishes alone cannot hide most structural cracks. Consumers are also discouraged from incorporating this product into the stucco system because of the high cost associated with using it. Another possible setback in opting for an acrylic finish, due to its highly visible nature, is the potential conflict between the desired aesthetic outcome and the need to reduce significant cracks.
More recently, the prior art involving new base and mesh systems have been advocated by various stucco trade organizations that employ polymer-modified coatings which are applied over the brown coat. Such solutions deal with the general field of stucco walls and teach away from specially addressing door or window corners. It is important to note that using a reinforcing fiber mesh embedded in a base coat is very costly, since it requires another coat of material to be applied over the whole structure. This option is many times presented to customers by plastering contractors, although due to the additional time and cost it is usually declined. When accepted, the success of the mesh system is most effective in controlling minor cracks on large, uninterrupted surfaces and not at locations of most stress, specifically openings with square corners. See Base and Mesh Systems for Crack Reduction (March 2011) Stucco Manufactures Association, Newport Beach, Calif.
The trend in the art is to use prior art base coats with newer polymer-modified coatings as described in literature by Merlex for their BaseX product line. The known prior art patent literate described below discloses various large scale control joint methods that do nothing to address building movements at door or window corners.
U.S. Pat. No. 1,355,756 issued on Oct. 12, 1920 to Earley is entitled “Flexible Joint for Stuccoed Buildings” discloses a spacer system to create an air space near doors and windows to allow surrounding stucco work to move without directly pressing upon stucco applied over door or window joints. The product is very similar to a casing bead around a frame, in that it functions more as a plaster stop and does not distribute the concentration of stress that accumulates and is released at the corners of windows and doors; thus cracks still form.
U.S. Pat. No. 4,651,488 issued on Mar. 24, 1987 to Nicholas et al is entitled “Expansion Joint for Plaster Walls” and discloses a unitary extruded plaster screed expansion joint system to reduce stucco cracks.
U.S. Pat. No. 5,699,638 issued on Dec. 23, 1997 to Maylon is entitled “Stucco Arch Casing Bead” and discloses an arch casing bead with a mounting flange and other features to facilitate the construction of stucco archways.
U.S. Pat. No. 7,874,123 issued on Jan. 25, 2011 to Mariarz is entitled “Stop Bead for Separating Stucco Material from a Frame of a Window or Door” and discloses a slight variation to the traditional L-Bead system used to reduce the time and cost of applying stucco near a door or window. Here again, no corner provisions are considered, as the Mariarz disclosure is concerned with the speed of stucco application and not the reduction of subsequent cracks. Thus, there is a long felt need in the art for the embodiments of the present invention.